A Privacy-Preserving Machine Learning Scheme Using EtC Images

TL;DR

This paper introduces a privacy-preserving machine learning scheme utilizing encrypted images (EtC) that maintains high performance without degradation, enabling secure and efficient facial recognition and other ML tasks.

Contribution

It presents a novel property of EtC images allowing direct application to machine learning algorithms without special decryption steps, preserving accuracy.

Findings

No performance degradation in SVM and random forests with EtC images

Effective facial recognition using encrypted images

Demonstrated compatibility with JPEG compression

Abstract

We propose a privacy-preserving machine learning scheme with encryption-then-compression (EtC) images, where EtC images are images encrypted by using a block-based encryption method proposed for EtC systems with JPEG compression. In this paper, a novel property of EtC images is first discussed, although EtC ones was already shown to be compressible as a property. The novel property allows us to directly apply EtC images to machine learning algorithms non-specialized for computing encrypted data. In addition, the proposed scheme is demonstrated to provide no degradation in the performance of some typical machine learning algorithms including the support vector machine algorithm with kernel trick and random forests under the use of z-score normalization. A number of facial recognition experiments with are carried out to confirm the effectiveness of the proposed scheme.